State which of these two Group 2 nitrates needs the higher temperature before decomposition begins. Explain your answer.
Once decomposition is complete, the $0.01\ \text{mol}$ sample of magnesium oxide is taken and increasing quantities of water are added to it, with stirring, until no solid remains. This is then repeated with the $0.01\ \text{mol}$ sample of strontium oxide. Identify the sample that needs the greater amount of water for all the solid to dissolve. Explain your answer by referring to the solubilities of the products formed when water is added to the oxides. You should refer to relevant energy terms in your answer.
The nitrogen dioxide released when $0.0100\ \text{mol}$ of strontium nitrate decomposes is dissolved in water. The oxidising agent $\text{H}_2\text{O}_2(aq)$ is then added to make $150.0\ \text{cm}^3$ of a solution in which nitric acid, $\text{HNO}_3$, is the only nitrogen-containing product. Calculate the concentration, in $\text{mol dm}^{-3}$, of $\text{HNO}_3$ in the $150.0\ \text{cm}^3$ of solution.
The $\text{HNO}_3$ in $25.0\ \text{cm}^3$ of this solution is neutralised by $0.125\ \text{mol dm}^{-3}$ $\text{NaOH}(aq)$. Calculate the minimum volume, in $\text{cm}^3$, of $\text{NaOH}(aq)$ required. Give your answer to three significant figures.